Related papers: Transversity and Meson Photoproduction
We reconsider the option of extracting the transversity distribution by using interference fragmentation functions into two leading hadrons inside the same current jet. To this end, we perform a new study of two-hadron fragmentation…
Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five…
The transversity distribution was recently extracted from deep-inelastic scattering processes producing hadron pairs in the final state. Together with a specific chiral-odd di-hadron fragmentation function, it is involved in the elementary…
The observation of the quark transversity distribution requires another soft object sensitive to the quark's transverse spin. Dihadron fragmentation functions represent a convenient tool to analyze partonic spin, which can influence the…
To identify some way to measure the quark transversity, this thesis analyzes one-particle and two-particle inclusive deep inelastic scattering, where one and two of the outgoing hadrons are detected in coincidence with the electron. It is…
Accounting for transverse momenta of the quarks, a longitudinal quark spin asymmetry exists in a transversely polarized nucleon target. The relevant leading quark distribution $g_{1T}(x,k_T^2)$ can be measured in the semi-inclusive…
We estimate the leading order amplitudes for exclusive photon and meson electroproduction reactions at large Q^2 in the valence region in terms of skewed quark distributions. As experimental investigations can currently only be envisaged at…
We make a systematic calculation for polarized vector meson production in semi-inclusive lepton-nucleon deep inelastic scattering $e^-N\to e^-VX$. We consider the general case of neutral current electroweak interactions at high energies…
The single-spin asymmetry of unpolarized leptons scattering deep-inelastically off transversely polarized nucleons is studied in a partonic picture within a collinear twist-3 framework. Since this observable is generated by multi-photon…
We revisit the standard analysis of inclusive Deep Inelastic Scattering off nucleons taking into account the fact that on-shell quarks cannot be present in the final state, but they rather decay into hadrons - a process that can be…
Recent results for the photoproduction of mesons off nuclei are reviewed. These experiments have been performed for two major lines of research related to the properties of the strong interaction. The investigation of nucleon resonances…
An analysis of all possible polarization observables for the case of vector meson photoproduction from a nucleon target is presented. The question of which observables are needed to determine completely the basic photoproduction amplitudes…
The specificities of transverse polarization with respect to helicity of ultrarelativistic fermions are pointed out. For massless fermions, a covariant transversity four-vector is defined, up to a kind of gauge transformation. The…
Transversity distribution describes the quark transverse polarization inside a transversely polarized nucleon. It is the less known leading-twist piece of the QCD description of the partonic structure of the nucleon. Transversity can be…
Exclusive reactions induced at high momentum transfer in few body systems provide us with an original way to study the production and propagation of hadrons in cold nuclear matter. In very well defined parts of the phase space, the reaction…
The measurement of transverse spin effects in semi-inclusive deep-inelastic scattering is an important part of the COMPASS physics program. From the analysis of the 2002-2004 data, new results for the transverse target spin asymmetry of…
The investigation of transverse spin and transverse momentum effects in deep inelastic scattering is one of the key physics programs of the COMPASS collaboration. In the years 2002-2004 COMPASS took data scattering 160 GeV muons on a…
In inclusive deep-inelastic lepton-hadron scattering multi-photon exchange between the leptonic and the hadronic part of the process causes single spin asymmetries. The asymmetries exist for a polarized target as well as a polarized…
Heavy flavour production like $J/\psi$ and $D$- meson production in scattering of electrons/unpolarized protons off polarized proton target offer promising probes to investigate gluon Sivers function. In this talk, I will summarize our…
The role of the nucleon resonances ($N^*$) in $\omega$ photoproduction is investigated by using the resonance parameters predicted by Capstick and Roberts. The contributions from the nucleon resonances are found to be significant in various…